Unable to preview or listen to new downloads.

Limewire was working perfectly a while back in December, but I did a software restore and it hasn't been the same since... I can't listen to any new downloads, and Quicktime has been giving me a really hard time. I'll click on 'Launch', and nothing happens. I don't know if I'm being too vague, but if someone can help me out with what information given, that would be great. I don't know much about computers, so please be detailed! Thanks -- Destiny